{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Accessing Python Syntax Trees"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "It is also possible to access code that is written in Python. This works using the `ast` module, and works as follows:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Module(body=[FunctionDef(name='f', args=arguments(args=[arg(arg='x', annotation=None), arg(arg='y', annotation=None)], vararg=None, kwonlyargs=[], kw_defaults=[], kwarg=None, defaults=[]), body=[Return(value=BinOp(left=BinOp(left=BinOp(left=Num(n=2), op=Mult(), right=Name(id='x', ctx=Load())), op=Add(), right=BinOp(left=Name(id='y', ctx=Load()), op=Pow(), right=Num(n=2))), op=Add(), right=Num(n=5)))], decorator_list=[], returns=None)])\n"
     ]
    }
   ],
   "source": [
    "SRC = \"\"\"\n",
    "def f(x, y):\n",
    "    return 2*x + y**2 + 5\n",
    "\"\"\"\n",
    "\n",
    "import ast\n",
    "tree = ast.parse(SRC)\n",
    "\n",
    "print(ast.dump(tree))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "It is possible to transcribe the expressions here into the form discussed earlier."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "2*x + y**2 + 5\n"
     ]
    }
   ],
   "source": [
    "from pymbolic.interop.ast import ASTToPymbolic\n",
    "expr = ASTToPymbolic()(tree.body[0].body[0].value)\n",
    "print(expr)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "But beware when defining languages this way. Python has very well-defined semantics, and the user will expect that your way of executing their code is a good match for their mental model of what the code should do. As such, it may be better to start with a \"blank slate\" in terms of language design, so as to not run afoul of already formed expectations."
   ]
  }
 ],
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    "name": "ipython",
    "version": 3
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   "file_extension": ".py",
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